Low-energy pulses mean safer heart defibrillation

WHEN the paramedics reach for the defibrillator to treat cardiac arrhythmia, they know the treatment comes at a cost: the powerful bolt of electricity can be painful if the patient is conscious, and may damage tissues around the heart.

However, the "brute force" approach is considered the only reliable way to combat the disordered pattern of electrical activity in the structurally complicated heart, say Flavio Fenton at Cornell University in Ithaca, New York, Stefan Luther at the Max Planck Institute for Dynamics and Self-Organization in Göttingen, Germany, and their colleagues.

But the team have found that even a mild electric shock - with around 10 per cent of the energy used in standard defibrillation - restores normal heart rhythm to a few isolated areas of dogs' hearts. They also discovered that by carefully timing the delivery of five low-energy pulses these areas expanded to fill the entire heart (Nature, DOI: 10.1038/nature10216).

"Progressively the system goes into a synchronised state and returns to normal rhythm," says Fenton.

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